TH‐AB‐BRB‐04: Dosimetric and Clinical Benefits of Conformal Radiotherapy Plus Volumetric Modulated Arc Therapy in the Treatment of Non‐Small Cell Lung Cancer

Abstract

Purpose:The purpose of this manuscript is to investigate the dosimetric and clinical benefits of a technique by combining conformal radiotherapy (CRT) plus volumetric modulated arc therapy (VMAT) in the treatment of non‐small cell lung cancer (NSCLC).Methods:There were 200 NSCLC patients analyzed retrospectively and treated by CRT, CRT plus VMAT, and full course of VMAT, respectively. Dosimetric differences, radiation pneumonitis (RP) rates and their correlation were investigated.Results:The number of patients analyzed in CRT, CRT plus VMAT and full course of VMAT were 42, 28, and 53, respectively. The V93 and V95 (percent volume covered by isodose line) of planning target volume (PTV) were improved from 95.7%±2.2% and 94.5%±2.4% in CRT to 97.9%±4.6%, 98.3%±3.2% and 96.3%±5.8%, 97.1%±4.1% in CRT plus VMAT and full course of VMAT, respectively. CRT plus VMAT improved the PTV coverage compared with CRT in a cost of higher spinal cord maximum dose (p=0.02), larger lung volume receiving 5 Gy (V5, p=0.02) and mean lung dose (MLD) (p=0.04), and decreased the low dose lung volumes compared with VMAT. The RP rates were 26%, 39% and 49% for CRT, CRT plus VMAT and VMAT, respectively. V5 was significantly associated with RP and had a threshold of 60% and 65% for CRT plus VMAT and VMAT, respectively, to limit the RP rate <30%.Conclusion:CRT plus VMAT is a promising with increased target coverage compared with CRT and reduced low dose lung volume and RP compared with full course of VMAT in the treatment of NSCLC. V5 was significantly associated with RP and with a predicted threshold of 60% and 65% for CRT plus VMAT and VMAT, respectively, to limit the RP rate <30%. Clinical trials with large population are needed to further verify the benefits of CRT plus VMAT in the treatment of NSCLC.